[GRASS-dev] Re: [GRASS GIS] #398: r.watershed with MFD

[GRASS GIS]

#398: r.watershed with MFD
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  Reporter:  mmetz        |       Owner:  grass-dev at lists.osgeo.org
      Type:  enhancement  |      Status:  reopened                 
  Priority:  minor        |   Milestone:  7.0.0                    
 Component:  Raster       |     Version:  svn-trunk                
Resolution:               |    Keywords:                           
  Platform:  Unspecified  |         Cpu:  Unspecified              
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Comment (by mmetz):

 Helena Mitasova and Michael Barton asked previously about backporting
 r.watershed with MFD to grass6. Now that develbranch_6 stays as version
 6.5.svn, does someone have objections against backporting r.watershed from
 trunk to develbranch_6?

 It would be backported with the following modifications for backwards
 compatibility:

 disable MFD by default, it will be enabled with a new -f flag. I don't
 want to (ab)use the -s flag of trunk because it has the opposite meaning.
 The -s flag will be removed.

 RUSLE LS and S factors will again be multiplied by 100, as before. The
 output raster type of the LS and S factors has to be changed to DCELL
 though, otherwise MFD won't work, because flow accumulation needs to be of
 type DCELL for MFD, i.e. always, and the segmented mode uses the same
 function for writing out any variable of type DCELL. Previously, LS and S
 factor were stored as type DCELL, but both in segmented mode and in ram
 mode written out as type (CELL) (factor * 100). This change from CELL to
 DCELL can not be reverted, at the same time supporting flow accumulation
 output as type DCELL, without a lot of rewriting, actually more rewriting
 than was necessary to implement MFD support. The change from CELL to DCELL
 for flow accumulation and the RUSLE factors will hopefully not break
 scripts.

 I would need some help on how to properly backport the various changes
 from trunk to devbr6. According to the svn howto, svn merge backports one
 particular change if I got that right.

 Markus M

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Ticket URL: <http://trac.osgeo.org/grass/ticket/398#comment:8>
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